Increasing concentrations of CO2 and other gases seem
likely to warm the earth in the next century. We examine opportunities to
prepare for the consequences, focussing on options that are rational even
if one is skeptical about global warming.

Some responses can be postponed. But many low-cost opportunities
will slip away if we fail to act; and reaching a consensus on what is fair
is easier when the consequences seem remote. We conclude that some changes
in land use and water allocation should be implemented today, even if effective
dates are several decades in the future.

INTRODUCTION

In the last three decades, a scientific consensus has emerged that
humanity is gradually setting in motion a global warming by a mechanism commonly
known as the "greenhouse effect." If current trends continue, our planet
is likely to warm 3-5oC in the next century--as much as it has
warmed since the last ice age. Such a warming would raise sea level a meter
or more, and threaten water supplies, forests, and agriculture in many parts
of the world. In response, the U.N. General Assembly has created an Intergovernmental
Panel on Climate Change to develop a plan for decreasing worldwide emissions.
However, climatologists have generally concluded that it is too late to
prevent a one or two degree warming.

Should planners begin to prepare for the consequences of the greenhouse
effect? The need to respond today depends on (1) the likelihood of global
warming; (2) the magnitude of the impacts; and (3) the potential for anticipatory
measures to reduce adverse impacts if sea level rises or climate changes
as expected, without imposing substantial costs if the changes do not unfold.
Although the literature on the first two factors is extensive, the latter
issue has rarely been mentioned. As a result, some people assume that it
would be unwise to prepare for global warming until its eventuality and consequences
are firmly established.

In this article, we show that for many of the possible consequences
of global warming, one can develop anticipatory responses that would substantially
reduce adverse impacts of global warming with relatively little risk of the
response proving to be ill-advised should the expected effects of global warming
fail to unfold. After briefly summarizing the literature on the causes and
effects of global warming, we suggest a number of criteria for evaluating
response strategies, and present several example responses in detail. Although
most of the examples involve the United States, similar opportunities are
available in other countries. We hope that this article helps motivate planners
throughout the world to begin preparing for the uncertain consequences of
a global warming.

THE GREENHOUSE EFFECT:
CAUSES, EFFECTS, AND RESPONSES

The Swedish chemist Svante Arrhenius (1896) coined the term "greenhouse
effect" at the turn of the century: The water vapor and carbon dioxide found
naturally in the earth's atmosphere allows sunlight to penetrate but retains
outgoing infrared radiation, in a manner somewhat analogous to the glass panels
of a greenhouse. Arrhenius estimated that if the combustion of fossil fuels
were to result in a doubling of atmospheric CO2 levels, global
temperatures could rise 5oC.

Until 1957, scientists generally expected the oceans to absorb the
CO2 released by human activities. Since that time, however, we
have learned that only half the CO2 dissolves into the oceans,
and that atmospheric levels of CO2 are increasing (Keeling et al.
1982). For the last decade there has been a consensus among climatologists
that a doubling of C02--expected by the middle of the next century--would
raise global temperatures 1.5-4.5oc (Charney et al. 1979), although recent
assessments suggest that the warming could be greater (Lashoff 1989). Moreover,
a number of other gases released by human activities also have a greenhouse
effect, including methane, chlorofluorocarbons, nitrous oxide, and carbon
tetrachloride (Ramanathan et al. 1985).

Most of the consequences of global warming would result from one
of three physical changes: sea level rise, higher local temper- atures, and
changes in rainfall patterns (Figure 1). Sea level
is generally expected to rise 50-200 cm in the next century (Dean et al.
1987); such a rise would inundate 7,000 square miles of dry land in the United
States (an area the size of Massachusetts) and a similar amount of coastal
wetlands; erode recreational beaches 100-200 meters, exacerbate coastal flooding;
and increase the salinity of aquifers and estuaries (Titus 1989).

For most practical purposes, the rise in sea level would be uniform--both
geographically and seasonally--because sea level is a global process (although
the impacts would vary greatly). By contrast, climatologists generally expect
important seasonal and geographical variation in precipitation and temperature
changes; the warming, for example, is likely to be greatest in winter and
at higher latitudes. Unfortunately, no one can predict how the climate of
particular regions will change. Although there is a general expectation of
wetter winters and dryer summers in mid- latitude continental areas (Manabe
et al. 1986), the possibility of wetter summers can not be ruled out for any
particular location.

Nevertheless, a number of impacts now seem likely, largely because
the relatively certain increases in temperatures would overshadow the unknown
changes in rainfall. Higher temperatures would increase evaporation; hence
the Great Lake levels are likely to drop even if rainfall increases moderately
(Marchand et al. 1988). Snow packs will melt several weeks earlier, implying
that less water will flow into California's Central Valley (Lettenmaier et
al. 1989). Regardless of soil moisture, many crops fail when temperatures
exceed 100oF, which could become commonplace in the southeast (Peart et al.
1989); temperatures are also likely to exceed the tolerance of the dominant
forest tree species in the southeast (Urban and Shuggart 1989).

Table 1 presents some possible responses for several of the effects
of global warming. As the table indicates, the response will often involve
a fundamental choice between maintaining economic activities in their current
locations and preserving the environment. Coastal ecosystems can not migrate
inland and terrestrial ecosystems can not migrate north if blocked by development;
rivers can not remain unspoiled if their water is diverted for agricultural
and urban uses. As with most issues faced by planners, the political process
will have to make these tradeoffs; but conflicts can be minimized if strategies
are implemented in advance of the problem.

SETTING PRIORITIES

One of the most fundamental issues facing decision makers is whether
to implement responses today or defer preparation until the impacts are better
understood and more close at hand. The fact that global warming might eventually
necessitate a particular action does not necessarily imply that the action
should be taken today. On the other hand, the likelihood of global warming
is sufficiently well-established and the time it takes to develop a response
sufficiently long that deferring all preparation could lead us to overlook
opportunities to inexpensively prepare ourselves.

In evaluating potential responses to global warming, policy will
have to consider a variety of criteria:

Economic Efficiency: Will the initiative yield
benefits substantially greater than if the resources were
applied elsewhere?

Flexibility: Is the strategy reasonable for the
entire range of possible changes in temperatures, precipita-
tion, and sea level?

Urgency: Would the strategy be successful if implemen-
tation were delayed ten or twenty years?

Low Cost: Does the strategy require minimal
resources?

Equity: Does the strategy unfairly benefit some at
the expense of other regions, generations, or economic
classes?

Institutional feasibility: Is the strategy acceptable
to the public? Can it be implemented with existing
institutions under existing laws?

Unique or Critical Resources: Would the strategy
decrease the risk of losing unique environmental or cultural
resources?

Health and Safety: Would the proposed strategy
increase or decrease the risk of disease or injury?

Consistency: Does the policy support other national
state, community, or private goals?

Private v. Public Sector: Does the strategy minimize
governmental interference with decisions best made by the
private sector?

Although planners routinely consider these issues in addressing current
problems, the nature of global warming may alter their role in the planning
process. (1) While urgency usually means that a problem is imminent, in the
context of the greenhouse effect the question is whether the opportunity to
solve the problem is likely to vanish if no action is taken soon. (2) Equity
may be easier to achieve: solutions that take effect several decades hence,
for exampole, are less likely to be unfair since people have ample time to
adjust. Finally, (3) because current institutions were not designed with
global warming in mind, they may be unable to address the issue; on the other
hand, the magnitude of the problem may be great enough to compell legislators
to change laws that planners usually must accept as fixed.

Perhaps the greatest difference, however, is the difficulty of weighing
present versus future benefits. Classical microeconomics provides a framework
(e.g. cost-benefit analysis) for reducing all the criteria to economic efficiency,
except for institutional feasibility and equity, and circumvents the latter
problem by proposing that winners compensate those who lose from a policy
(this part of the theory is often overlooked by practitioners). For example,
"discounting" future benefits is often used to determine the "present" value
of costs and benefits in the distant future, but the procedure only addresses
economic efficiency; i.e. whether solving a problem now is superior to investing
the same level of resources in a trust fund that can be used to clean up the
problem later. Unfortunately, most governments can not simply establish
a trust fund. Some people assume that the analysis also indicates whether
an action today is superior to no action; but such an assumption implies indifference
regarding how many unsolved problems we pass on to future generations, since
it equates no action with establishing a trust fund.

Moreover, financial theory shows that the appropriate discount rate
equals the return on risk free investments (e.g. Treasury Bonds) plus a risk
premium reflecting the correlation between the return on the investment and
the overall success of the investor's portfolio. In the 1980s, the U.S. Office
of Management and Budget required federal agencies to use a 10% discount rate,
effectively assuming that benefits from federal policies are highly correlated
with the stock market and society's overall well-being. However, strategies
to prepare for the greenhouse effect would help the most if the consequences
are severe; hence these policies can be viewed as insurance, which implies
that the appropriate discount rate is less than the (real) return on Treasury
bonds and may even be less than zero, which produces nonsensical results
if an analysis is extended into the indefinite future.

Given the limitations of cost-benefit analysis, we suggest that
planners first concentrate on the "easy" solutions, that is, those that are
low cost; reasonable for the entire range of likely changes in climate; institutionally
feasible; urgent; and equitable. In mature fields of endeavor, the easy solutions
have already been implemented; but preparing for global warming is a new
field.

EXAMPLE STRATEGIES

Responses to climate change can be broadly divided into four
categories.

No action today where least-cost solutions could be
implemented as the problem emerges with existing technology
and institutions;

Anticipatory action, where it would be wise to take
concrete measures today;

Planning, where we do not need to physically change what
we are doing immediately, but where we need to change
the "rules of the game" now, so that people can respond
to new information in a way that furthers social goals;

Research and education in cases where it would take
decades to develop solutions and train people to carry
them out, or where the need to take action has not yet
been assessed.

We now examine examples of each type of response, identifying easy solutions
where possible.

No Action Today

The urgency of responding to climate change depends not only on
the severity of a potential impact, but also the extent to which taking action
today would diminish the ultimate cost of adaptation or allow us to avoid
problems that will be unavoidable if we wait before taking action. If the
solution to a problem is well-defined and can be implemented quickly, there
is little reason to take action.

Miller and Brock (1989) examine decision rules that governing releases
of water from reservoirs, which are generally based on historic climate variability.
For example, if the flood season is March to May and droughts are from July
to September, reservoir managers will typically lower the water levels by
the end of February to ensure adequate flood control capacity, and allow the
levels to rise in June so that there is adequate water in case of a drought.
If global warming advanced the flood season by one month, managers would
eventually shift the schedule of water releases; but there is no need to do
so today.

Similarly, the rise in sea level would eventually require the Republic
of Maldives to raise its inhabited islands, probably by mining certain coral
areas for material (Figure 2); seaside resorts will have to pump sand onto
eroding beaches (Figure 3); and levees will be necessary to protect cities,
but these activities can await the actual rise (Dean et al. 1987). Changes
in rainfall and temperatures will eventually lead farmers to shift crops (Adams
et al. 1989), but shifting today would be counterproductive.

Anticipatory Action

Nevertheless, studies have identified a number of instances in which
physical responses are appropriate even today, either by (1) incorporating
global warming into long-term projects that are already underway; (2) taking
actions today that without global warming might not be necessary until later,
if at all.

Incorporating Global Warming into Long-Term Projects

The rationale for doing so is that the outcome of projects initiated
today will be altered by the effects of global warming. Modifying plans
to consider global warming would frequently be an "easy" solution: The cost
of factoring climate change will often be a small percentage of the total
project cost; it is "urgent" because once the project is under construction
it will be too late to incorporate climate change. Because a consideration
of the greenhouse effect would often ensure that projects are adequate to
address current climate variability, it would often prove to be a useful
investment even if the projected global warming does not materialize as expected.
Two examples follow:

Sewers and Drains. Titus et al. (1987) examined the replacement
of a century-old street drain in Charleston, South Carolina (Titus et al.
1987). If designed for the current 5-year storm, such a system might be insufficient
if sea level rises one foot or the severity of the design storm increases
10 percent, necessitating a completely new system long before the end of
the project's useful life. On the other hand, installing slightly larger pipes
sufficient to accommodate climate change might cost only an additional 5
percent. In such a case, designing for an increases in precipitation might
prove to be worthwhile if these changes occur; even if they do not occur,
there would be some benefits because the system would provide protection during
the more severe 10-year storm. Wilcoxen (1986) made a similar argument regarding
the location of San Francisco's West Side Sewage Transport. Similar situations
wil occur throughout the world.

Commercial Forests. Because some commercial tree species live as
long as 70 years before being harvested, forest products companies may want
to reconsider location and types of species. For example, some types of
Douglas fir need at least a few weeks of cold winter temperatures to produce
seeds. Currently, companies concentrate planting efforts at the bottoms of
mountains, from which logs can be most readily transported; considering future
warming may lead them to plant further up the mountain or in colder regions.

In some cases, an "easy" solution may be to shift from long- lived
species that are vulnerable to climate change to those that are less vulnerable
or have shorter growing cycles. If two species are equally profitable today
but one would fare much better if climate changes, shifting to the latter
species involves little risk and might substantially help long-term profits.
Shifting to a species with a 20-year lifetime would enable harvests to take
place before climate changes enough to adversely affect growth, and would
make it easier to respond to climate change as it occurs.

Undertaking Projects Today because of Future Climate Change

In a few cases, where authorities are already contemplating public
works for which the economic justification is marginal, the prospect of sea
level rise or climate change might convince decision makers to proceed. For
example, a surge in the Thames River in the 1950s that almost flooded London
led the Greater London Council to develop plans for a massive movable barrier
across the river. Many questioned whether it was worth building. But the
fact that flood levels had risen steadily one foot every 50 years for the
past five centuries convinced their technical advisory panel that the barrier
would eventually be necessary; once that eventuality was recognized, there
was a consensus that the project should go forward (Gilbert and Horner 1984).

Constructing a project because of the greenhouse effect will rarely
if ever be an "easy" solution: It requires more certainty than incorporating
climate change into a project that would be undertaken anyway, because (1)
undertaking a new project requires the legislature or board of directors to
initiate major appropri- ations, rather than approve supplemental increases
and (2) the project can be delayed until there is more certainty. Even if
future impacts are certain, action is unnecessary unless the time it will
take for the impacts to occur is no greater than the time it will take to
design, approve, and build the project. Thus, only the near-term impacts
and those whose solution would take several decades to implement require remedial
action today.

Wetland Loss in River Deltas. In the United States, Louisiana
is already losing 100 square kilometers of land per year due to subsidence
and human alteration of natural deltaic processes. If current trends continue,
most of the wetlands will be lost by 2100 (Louisiana Wetland Protection Panel
1988.) But if sea level rise accelerates, this could occur as soon as 2050.
The immediacy of the problem is greater than these years suggest, because
the loss of wetlands is steady. Assuming the additional loss of wetlands
to be proportional to sea level rise, half the wetlands could be lost by 2030,
with some population centers threatened before then.

Whether or not sea level rise accelerates, the majority of wetlands
can only survive in the long run if society restores the natural process by
which the Mississippi River once deposited almost all of its sediment in
the wetlands. Because billions of dollars have been invested in the last 50
years in flood-control and navigation-maintenance projects that could be
rendered ineffective, restoring natural sedimentation would cost billions
of dollars and could take twenty years or longer. Because of the wide variety
of interests that would be affected and the large number of options from which
to choose, it could easily take another ten to twenty years from the time
the project was authorized until construction began.

Thus, if sea level rise accelerates according current projections,
and a project is initiated today, about half of the delta will remain when
the project is complete, while if is authorized in the year 2000, 60-70 percent
might be lost before it comes on line. By contrast, if sea level does not
accelerate, the two implementation dates might imply 25 and 35 percent losses
of coastal wetlands. Because a delay would not substantially reduce the costs
of such a project, and because there would be considera- ble benefits from
an earlier implementation date even if sea level rise does not accelerate,
it would be more economically efficient to authorize it today than ten hears
hence.

Elsewhere, the Nile Delta is eroding rapidly as a result of the Aswan
Dam (Broadus et al. 1986), and the capital of Nigeria is being moved from
Lagos in part because a major dam on the Niger river is causing shores to
erode 50 meters per year. Because sustaining deltas in the face of rising
sea level will require incrased sediment, planners at the World bank and other
international development agencies may want to reconsider the implications
of new dams along some rivers.

Purchasing Land could keep options open for water resources management
and protecting ecosystems. In regions where climate becomes drier, additional
reservoirs may eventually be necessary. However, because accurate forecasts
of regional climate change are not yet possible, water managers in most areas
cannot yet be certain that they will need more dams. Even in areas where
earlier snow melt or sea level rise is expected to necessitate increased
storage--such as California (Williams et al. 1988) and Philadel- phia/New
York (Hull and Titus 1986), respectively--the dams will not have to be built
for decades. Nevertheless, it may be wise to purchase the necessary land
today; otherwise, the most suitable sites may be developed, making future
construction more expensive and perhaps infeasible. A number of potential
reservoir sites have been protected by creation of parks and recreation
areas, such as Tocks Island National Park on the Delaware River.

Governments often purchase land to prevent development from encroaching
on important ecosystems. Particularly in cases where ecosystem shifts are
predictable, such as the landward migration of coastal wetlands, it may be
worthwhile to purchase today the land to which threatened ecosystems would
be expected to migrate. Even where the shifts are not predictable, expanding
the size of refuges could limit their vulnerability (Peters and Darling 1985)

Land purchases for allowing ecosystems to migrate have two important
limitations. First, they could probably only be used for protecting a few
strategic ecosystems. As a general solution, the cost would be prohibitive:
Protecting coastal wetlands would require buying most of the nation's coastal
lowlands; and many types of terrestrial species would have to shift by hundreds
of miles. Second, land purchases do not handle uncertainty well. If temperatures,
rainfall, or sea level change more than anticipated, eventually the land purchased
will prove to have been insufficient.

Planning: Changing the Rules of the Game

"Doubt is an unpleasant situation," Voltaire once wrote, "but certainty
is absurd." While some professions deal strictly with facts, planners must
look into the future, which is inherently uncertain. Thus, defining "rules
of the game"--how we respond to particular events should they occur--is often
more important to planners than taking concrete action. If an agricultural
region mmight be developed in 20 to 50 years, for example, the need is not
to build highways and sewers today but to determine where they would eventually
be located so that activities in the intervening years are consistent with
the long-term situation.

Although concrete action in response to global warming is necessary
today for only a few types of problems, defining the rules of the game may
provide "easy" solutions for a much wider class of problems. Doing so increases
flexibility: if climate changes, we are better prepared; if it does not, preparation
has cost us nothing. Political feasibility may be enhanced because it is
easier to reach a consensus when no one is immediately threaten- ed. Moreover,
such planning reduces risk to investors: although they still face uncertainty
regarding climate change and sea level rise, planning can prevent that uncertainty
from being compounded by uncertainty regarding how the government will respond.
Land use and water allocation provide two examples.

Land Use

Society may want to guide development away from areas where it might
conflict with future environmental quality or public safety. A primary
rationale for most local land-use planning is that by themselves, real-estate
markets do not always produce economically-efficient or socially-desirable
outcomes, because people do not bear all the costs or reap all the benefits
from their actions. As long as zoning and other land-use restriction are
implemented long before anyone would want to undertake the prohibited actions,
they do not unreasonably burden anyone--major reason these restrictions have
withstood legal and political challenges.

The institutional capabilities of planning are well-suited for addressing
environmental impacts of climate change when the direction of the impact
is known. Consider, for example, the goal of ensuring that development does
not block migration of ecosystems or preclude construction of a dam. Without
planning, the land could be vacated only by requiring abandonment with relatively
little advance notice, which would often require compensation and would always
hurt someone. Planning measures can either (1) limit development through
zoning (or purchase of land, discussed above), or (2) set up the social constraint
that ecosystems will be allowed to migrate, while allowing the market to
decide whether or not development should proceed given the constraint. (See
Howard et al. 1985. for options to retreat from the ocean coast.)

Limit Development: Zoning. The most common tool for controlling
land use are master plans and the zoning that results from them. A major
limitation is that zoning tends to be flexible in only one direction--allowing
more development; if a town elects a pro-development council that relaxes
zoning, it will be difficult to reimpose the restrictions later. Moreover,
as with purchases, one has to make an assumption regarding how far an ecosystem
needs to migrate; if temperatures, rainfall, or sea level change more than
anticipated, the ecosystem will not be protected in the long run.

Allowing the Market to Decide: Rolling Easements. These mechanisms
allow people to develop property, subject to the constraint that the development
will not be allowed to block migration of ecosystems. The primary rationale
is that preventing development is not economically efficient because in some
cases it might be worthwhile to develop a property even if it would subsequently
have to be abandoned; rollimg easements minimizes governmental interference
with private decisions, allowing markets to decides whether a property is
worth developing given available information. Another important advantage
is that neither uncertainties nor the long-term nature of global warming undermines
the feasibility of instituting it--in fact, they probably increase the
feasibility: unless or until the sea rises enough to inundate a property,
the policy imposes no costs. Thus, people who doubt the sea will rise or
are unconcerned about the distant future have few grounds to object.

With this situation in mind, the State of Maine (1987) has recently
issued regulations stating that structures along the ocean and wetland shores
would have to be removed to allow wetlands to migrate inland in response
to sea level rise. Numerous states prohibit seawalls along the ocean. Because
these rules do not interfere with the use of property for the next several
decades, they have a minimal impact on property values, and thus do not
deprive people of their property. The major limitation of this approach
is that it may be too flexible: if sea level rise begins to require a large-scale
abandonment, a state or local government may find it difficult to resist
pressure to repeal the rule.

An alternative that avoids the risk of backsliding is to modify
conventions of property ownership. One example would be long-term leases
(or fee simple determinable)interests in land, which expire at a remote date
or when a "condition" occurs (e.g. high tide rises above a property's elevation),
with property reverting to the government or a private conservancy. Although
the leaseholders (or owners of the fee simple) would want free renewals to
their leases (or invalidations of the reversionary interest), conservancy
groups would have little problem saying "no," and local governments--not to
mention the courts--find it easier to enforce contracts (or and interests
in land) than regulations.

Rolling easements could be created either as a part of a process
for permitting coastal development or through eminent domain purchases (Titus
1986.) Although they would involve some institutional changes, the changes
would not be unprecedented. National Park Service aquisitions often involve
conversion of property ownership to leases the expire upon the former owner's
death, and the prinipal of conditional ownership is generally taught to
beginning real estate agents (Galaty et al. 1985). Property on coastal
barrier islands on Babylon, New York and Pensacola Beach, Florida is under
long-term lease. Perhaps most importantly, rolling easements have long been
recognized by the common law of Texas.

Water Allocation

.

In the southwestern United States, the water supply in- frastructure
is guided by policies embedded in contracts and laws that prescribe who gets
how much water. Many of these rules are not economically efficient; water
is wasted because of rules that do not allow people with too much water
to sell it to people with too little. In many cases the equity of the formulas
is sensitive to climate; during wet periods, everyone may have plenty, while
in dry periods some get enough while others get none. Many ways by which
the impact of climate change might be reduced are already being advocated
in order to address current climate variability: legalizing water markets;
curtailing federal subsidies which lead to waste by keeping prices artificially
low; and modifying alloca- tion formulas. (Gibbons 1986; Bureau of Reclamation
1987).

Nevertheless, the changes required by global warming requires may
be different in one crucial aspect: the effective date in any rule changes.
Because the most severe changes in rainfall from the greenhouse effect are
still decades in the future, the problem can be addressed even if the effective
date is not until 2020. This situation may enhance the political feasibility
of instituting a response today, since no one need be immediately threatened.
By contrast, if planning is deferred another twenty years, the impacts of
climate change may become too imminent for potential losers to agree to the
necessary changes.

Increasing our Understanding: Assessments, Research, and Education

The fact that a particular problem will not require solutions for
a few decades does not necessarily mean that society should not begin preparing.
In some cases, the necessary solutions are decades away; in most cases, no
one has systematically examined the costs and results of various options.
We now examine three vehicles for expanding our knowledge.

Strategic Assessments.

Strategic assessments seek to determine whether, when, and how one
should respond to global warming, based on what we know today. In some cases
they formally assess the costs and benefits of alternative responses; in others
a qualitative analysis is sufficient.

Any organization that makes decisions whose outcomes stretch over
periods of thirty years or longer should examine the implications of climate
change. In many cases, these studies can use existing analytical tools, and
hence they are relatively inexpensive. From the standpoint of economic efficiency,
these assessments are good investments. If they reveal that action today
is worthwhile, the savings from such action can be orders of magnitude greater
than the cost of the study. Even if they show that no action is necessary,
many organizations will find it useful to know that their projects are not
vulnerable, and the studies will contribute to society's understanding of
the magnitude of the impacts of global warming.

These assessments can be implemented either as supplements to evaluations
of specific projects, or as special studies focusing on particular problems
or programs. The most cost-effective strategic assessments are those conducted
as a routine part of the evaluation of ongoing projects. Because they are
oriented toward a specific near-term decision, they are not likely to be ignored.
Their cost is often minimal because they supplement existing studies and
hence have little overhead. The Corps of Engineers has announced that it
intends to estimate the impacts of global warming in future feasibility studies
and environmental impact statements for coastal projects; and the Council
of Environmental Quality is considering the possibility of requiring other
federal agencies to consider climate change in environmental impact statements.
Table 2 lists other examples.

Agencies with many potentially-vulnerable activities may need program-wide
assessments. In some cases, the combined economic impact of climate change
can be summarized by a single variable, such as federal insurance claims.
On the other hand, some programs face a variety of impacts, each of which
must be examined separately.

Finally, legislative commitees, National Academies of Sciences, nnprofit
institutions, and intenational organizations may have to conduct problem-oriented
assessments for problems that are explicitly the responsibility of no one
while implicitly the responsibility of several different groups. The combined
impacts of farm closures and forest dieback raises land-use questions that
would be outside the scope of any single organization. Water resource problems
requiring the participation of several groups would include potential impacts
of increased agricultural water demand on aquifers and the levels of the
Great Lakes and the flow of rivers that pass through more than one country.

Figure 4
illustrates the relationship between the different types of assessments for
a hypothetical evolution of society's response to wetland loss from sea level
rise. In the example, federal and state programs are unable to address the
problem, although isolated local governments, in response to particular projects,
are able to issue permits tha solve the problem. Because no institution has
the responsibility to protect wetlands as sea level rises, a Congressional
committee assesses the entire problem, which leads to legislation. In response
to thenew Act, federal and state program assessments develop guidelines.
Given the new regulations, developers reassess the viability of planned projects,
while conservancies decide whether to offer to buy the property.

Research and Development

These expenditures could often be economically justified in cases
where immediate physical responses could not be. Most of the impacts of climate
change could at least theoretically be mitigated, but in many cases, effective
solutions have not yet been developed. Like strategic assessments, the value
of the research is potentially the savings it makes possible.

Research is also a vehicles by which one generation improves life
for succeeding generations. Even if the economic efficiency of taking action
to mitigate impacts can not be demonstrated, it seems only fair for this generation
to provide solutions to accompany the problems we pass to the next generation.

Table 3 lists a number of research questions whose solution would
assist adaptation. However, for the most part, strategic assessments have
not been undertaken to determine the cost and probability of developing solutions
or the magnitude of potential savings that might result, so it is difficult
to be certain that the research would benefit society. The most noteable
exception is improvement in estimates of future climate change and sea level
rise. Although many responses warranted in spite of current uncertainties,
better projections would improve planining for every impact of global warming.

Education

Efforts to prepare for climate change can only be as enlightened
as the people who must carry them out. Education must be critical component
of any effort to address the greenhouse effect because (1) there will be an
increased need for personnel in some professions, (2) people in other professions
will need to routinely consider the implications of global warming, and (3)
an informed citizenry will be necessary for the public to support the public
expenditures and institutional changes that may be required.

For many professions, the likelihood of a major expansion due to
global warming will depend on how society ultimately responds to global warming.
Will our response be in agriculture be primarily to develop new crops to
grow on existing farmland (plant scientists) or to facilitate the migration
of farmers to newly productive areas (planners)? Will our response to coastal
wetland loss be to remove development from lowlands so that they can migrate
naturally (planners), or to maintain existing land uses and support existing
wetlands artificially (hydrologists and ecologists)?

Nevertheless, the demand for coastal engineers will almost certainly
increase as cities erect levees and resorts pump sand onto their beaches.
An unfortunate paradox is that at the very moment when the public is becoming
increasingly concerned about sea level rise, and the need to develop new environmentally-sensitive
responses, the field's founding fathers are retiring and are not always being
replaced.

Professionals in various disciplines must be educated about global
warming so that decisonmakers can consider its implications. This process
has proceeded farthest in the case of sea level rise, where federal and state
agencies have sponsored several large conferences on the subject each year
since 1983. This process is now beginning to unfold in the fields of utility
planning and water-resource management, and may soon emerge in other fields.

With the exception of universally-recognized crises such as war and
disease, governments do not usually take the lead in creating public awareness.
In the short run, that function is generally carried out by the news media;
in the long run, it is performed by school systems. Nevertheless, governments
can support these institutions by sponsoring public meetings and translating
the results of technical studies into brochures and reports that are accessible
to reporters, teachers, and the general public.

CONCLUSION

History offers few examples in which society undertook actions for
the sole purpose of heading off a problem that was not expected for decades
or centuries. Yet the Thames River Barrier, the U.S. Constitution, and international
efforts to control world population illustrate that people can plan for the
very long run when a present-day crisis puts an issue on the table. Once
the public decides that it wants a problem solved, it is almost always willing
to pay the extra cost of ensuring that the solutions do more than merely delay
the day of reckoning.

The worldwide reaction to recent warm years suggests that there may
soon be a public consesnus to solve the problems associated with the greenhouse
effect. But unless planners begin preparing rational responses, politicians
will not know what to do when they are ready to act. In some cases they
may be willing to commission studies and wait. But they are just as likely
to act (or not act) based on whatever options are available at the time.
Even if better options are discovered later, there is no guarantee that
there will be a public outcry to revisit the issue.

The example responses we have outlined suggests that for most problems,
one can envision a number of easy solutions that would at least begin to address
the problem without arousing a constituency in opposition or subsequently
appearing to be ill-advised. The examples also suggest that in many cases,
the more costly options necessary to solve the whole problem would still prove
to be good investments even if the climate does not change as expected.

Because of the severity of the potential impacts, it is completely
appropriate for policy makers and the public to focus primarily on measures
to limit the extent to which humanity raises the earth`s temperature in the
years ahead, an issue outside the domain of most planners. Nevertheless,
past and current emissions suggest that it is too late to completely prevent
a change in climate, so we will have to learn to live with the consequences.
Although planners are sometimes frustrated by the futility of focussing politicians'
attention on events beyond the next election, global warming may be an opportunity
to help them show the voters that they are thinking about the type of world
we pass on to future generations. But whether the politicians lead or follow,
they public will have to decide the type of world we plan to achieve: If
something has to give, should our priority be to maintain current patterns
of land and resource use, to avoid tax increases, or to protect the environment?

Utility Company Is size of proposed power plant optimal given projected climate change?

City Engineer Should New Drainage Facilities Be Designed with extra margin for sea level rise and possible increased rainfall.

Water Resource Is Dam Designed Properly? Would itsAgencies Benefits Be Different if climate changes?Federal Agency Would the Environmental Impacts of the Developing EIS Project Be Different if Sea Level Rises of climate changes than currently assumed.Local Hazard Planner Is it safe to build in an aera that is barely outside the floodplaine.Program OrientedResearch Director For which impacts can we develop a solution? What would be the costs of the research and the potential benefits of anticipated solutions.

Utility Company Does System Capacity Need to Be Expanded? If not, when would it be necessary

Flood Insurance By how much would claims on the program increase? Does expanding program to include erosion increase or decrease impact of climate change?

Agricultural Do current farm programs help or hinderPlanners adjustments climate change might require Public Health Would climate change increase the Agencies incidence of malaria and other tropical diseases in the United States.

Air Pollution Does climate Change Imply thatAgencies current regulatory approach should be supplemented with incentive systems, new chemicals, or relocation policies?

Problem-OrientedNatural Resource Do we need a program to aid the survivalAgencies of forests and other terrestrial ecosystems?

Federal and State Which options would ensure long-termAgencies survival of Louisiana's coastal wetlands?

Wetland Protection How do we ensure that wetlands canAgencies migrate as sea level rises

Canada and What is the best way to manage fluctu- United States ations in levels of Mississippi River and Great Lakes

State Coastal Zone Would State Provide Necessary Funds toAgencies City Planners hold back the sea on barrier islandsOn Barrier Islands If state won't provide funds, wouldCommunities the town bear the cost of holding back the sea or adapt to a retreat. Are current erosion and flood programs consistent with long-term response?

Water Resources What should be done to address increasedAgencies salinity in Sacramento Delta.

Air Pollution Will climate change alter the resultsAgencies of current air-pollution strategies

Public Utility Should Power Companies Be Building ExtraCommissions Capacity for Increasing Demand?

TABLE 1: EXAMPLE RESPONSES TO GLOBAL WARMING Effect

Economy shifts to Accommodate the Environment Environment changes to Accommodate the EconomyBeach Erosion from SeaLevel RiseAllow shores to retreat; prohibitprivate construction of seawalls; setnew houses farther back from the shoreDredge sand from offshore and place iton the beachInundation of lowlandsRemove structures as shoreline retreatsConstruct bulkheads to protect housesfrom inundation and lose wetlandsRiverine Flooding Due toIncreased Storm SeverityElevate houses on pilings or prohibitconstruction in new floodplainConstruct dams to moderate river surges;construct levees to contain river flowDecreased Rainfall Threatens Water suppliesConserve water; relocate water-intensiveactivities to where water is more plent-ifulConstruct dams to provide seasonal sto-rage of water; construct pipelines andaqueductsHotter and dryer disruptagriculture Marginal farms are abandoned and newregions in wetter and cooler areas arecultivated. Increased irrigation necessitatesadditional water-supply infrastructure.Climate change and sealevel rise make naturepreserve less hospit-able for wildlifeExtend park boundaries inland in thecase of sea level rise, create new parkin a more favorable climate.Artificially feed animals; providewarming hut (i.e. convert park to zoo.)Hotter temperaturesbecome a nuisanceIncreased migration to colder areas. Increased air conditioning results inincreased power consumption conditioningSki conditionsdeteriorateSki resorts relocate to higher latitudesIncreased pressure to convert mountainlake to reservoirs for snowmaking

TABLE 3: Example Research Problems and Applications

Research Problem Application

Synergistic impacts of CO2, Shifts in Mix of Trees and crops,climate change, and air drought-tolerant crops.pollution on plants.

Shifts in habitats of birds, Restoration Ecology: rebuildingfish, and land animals. ecosytems that are lost.

Ability of Wetlands and Mechanisms to accelerate verticalcoral reefs to keep up growthwith sea level

Erosion of beaches due to More efficient placement ofsea level rise and changing sand when beaches are restoredwave climate.Ability of alternative plant Develop Heat and Drought strains to tolerate harsh Resistant Cropsclimate.

Magnitude of changes in All Responses to Global Warmingsea level and regionalclimate

Shifts in microorganisms that Long-term water supply planning currently impair water quality in tropical areas.

Figure Captions Figure 1: Overview of the Causes and Effects of Global
Warming, Before Society Responds Figure 2: Tulhadoo, Baa
Atoll, Republic of Maldives. Many coastal barrier and atoll islands throughout
the world will have to be raised as sea level rises. Figure 3 Example
relationship between strategic assessments. .